# 字典的元素的增加, 修改,删除; 并观察输出;

# 定义字典
student = {'name': '张三', 'age': 20, 'grade': 85}

# 增加元素
student['class'] = '软件1801'
print("增加元素后的字典:", student)

# 修改元素
student['grade'] = 90
print("修改元素后的字典:", student)

# 删除元素
del student['age']
print("删除元素后的字典:", student)